1. Field of the Invention
Aspects of the present invention relate to the determination and display of a toner residual quantity. More particularly, aspects of the present invention relate to an apparatus and a method of displaying a toner residual quantity in which it is determined whether or not a second prediction of toner residual quantity calculated based on the actuating time of a toner supply motor is within a predetermined range of a first prediction of toner residual quantity calculated using a dot count method and in which the second prediction of toner residual quantity is displayed based on the determined result.
2. Description of the Related Art
Printing machines or image forming apparatuses print an image on a sheet of paper by forming an electrostatic latent image, corresponding to data to be printed, which may be input from an external device, onto a photosensitive medium such as a photosensitive drum or a photosensitive belt, developing a toner image by supplying a predetermined developing agent such as a toner to the photosensitive medium on which the electrostatic latent image was formed, and transferring the toner image onto the sheet of paper.
Image forming apparatuses use a toner as an image forming medium. In image forming apparatuses, a toner amount is gradually reduced as an image is formed. Image forming apparatuses typically have an apparatus for sensing an amount by which toner is reduced in an image forming operation. This sensing may be done by a dot count method.
The dot count method is a method of analyzing a laser signal of an exposed laser scanning unit (LSU) in a developing unit, using this information to calculate how much toner will be used in an image forming apparatus and calculating a toner residual quantity by subtracting an amount of toner used from an original amount of toner. The time in which the laser signal is scanned has a proportional relationship with the amount of toner that is used in developing the image scanned by the laser signal. Therefore, the toner residual quantity can be predicted by using the proportional relationship.
Only, a problem occurs that accuracy cannot be guaranteed when calculating a toner residual quantity using the dot count method. That is, the toner usage of the image forming apparatus is affected by various variables, and these variables are overlooked when the toner residual quantity is calculated using the dot count method.
FIG. 1 is a graph that illustrates an error generated in case of calculating a toner residual quantity using a conventional dot count method. {circle around (0)} represents an actual residual quantity of toner as a function of time. {circle around (2)}represents a calculated residual quantity of toner as a function of time if the amount of toner usage is overestimated and the amount of toner remaining is therefore underestimated. In such a case, a warning message informing a user that the toner supply must be replaced may be needlessly generated even though an adequate amount of toner remains. {circle around (3)} represents a calculated residual quantity of toner if the amount of toner usage is underestimated and the amount of toner remaining is therefore overestimated. In such a case, a warning message informing a user that the toner supply must be replaced is not generated in time and the toner may run out in the middle of an image forming operation without the user being warned in advance.
That is, the conventional apparatus for displaying a toner residual quantity has a problem that a toner remaining amount value displayed may not be accurate and a user may not be adequately informed as to the exact time that a toner supply must be changed.